Method of improving the properties of activated bauxite and product thereof



Patented Oct. 14, 1930 I UNITED. STATES ammonia o. IBENNER, or NIAGARA rALLs, AND ALFRED PAUL rrromrson, OF J'ACK PATENT OFFICE SON HEIGHTS, NEW YORK, ASSIGNOlR-S TO GENERAL CHEMICAL COMPANY, OF NEW YORK, N. Y., A CORPORATION or NEW-Yon: I

METHOD or maovme" 'rn'n rnornarms or ACTIVATED BAUXI'IE AND raonuc'r rnnanor No Drawing.

- drating the natural mineral bauxite under the influence of heat, and has been adapted to a variety'of purposes such as decolorizing, purifying, and absorbent compound for mineral oils and solutions of various organic and inorganic mixtures; or as an agent for the urification of substances of this character y the elimination of sulfur. Moreover, we have discovered that activated bauxite functions as a catalyst to catalyze certain gaseous reactions as for example set forth in our United States application, Serial No. 119,739, dated June 30, 1926, and Serial No. 162,571, dated January 21, 1927.

One of the chief factors in determining the eificiency of the bauxite is considered tov be the pore-space of .the activated mineral. Ac-

tivation of the natural mineral results from the liberation of water therefrom, forming a substantially dehydrated and porous material. A high grade activated bauxite has a large portion of pore-space, and in general it maybe said that the efliciency is proportional to the pore-space, other conditlons remaining the same. Hovxever, activated bauxites which have a large proportion of pore-space are normally quite soft and brittle,-and 'c'rumble badly in the mechanical operations required in their preparation and reactivation. It is the object of our invention to provide a process for increasing the physical strength and resistance to mechanical disinte ration of such activated bauxites without ecreasing their efiiciency as catalysts, adsorbents, decolorizers, and so forth. v

According to our invention the activated bauxite isimpregnated with salts, Clparticularly nitrates, of the heavy metals an the impregnated product subsequently i ited to artificially produce the oxide of t e heavy metal uniformly distributed throughout the bauxite to act as a binder.

For example British Guiana bauxite activated by i nitin to a temperature of about for our hours to drive out most Application filed January 21, 1927. Serial No. 162,569.

,Preferabl the activated bauxite iscooled in vacuo an the impregnating solution introduced Without the admission of air. Upon the release of the Vacuum, the metal salt solution is forced into the pores of the bauxite by external or atmospheric pressure. The solution is then drained off and the impregnated bauxite is gradually brought up to a temperature of LOO-450 C. at which temperature it is ignited for about four hours. The resulting product is found to be much less friable than the unimpregnated bauxite and to have increased in hardness to about 4.5, this representing a very material increase over the untreated bauxite. Likewise the product is foundto have-a catalytic activity at least equal to if not greater than the unimpregnated substance, and its absorbing efficiency is but slightly less than the untreated material.

The impregnating liquid preferably con .sists of about a 20-25% solution of the heavy metal. salt made u by adding about one pound of the anhy rous metalhc salt or its equivalent to three to four pounds of water. While we have specified the use of ferric nitrate assuitable impregnating salt, the sulfate orchloride of iron ma be used though slightly. less effectively. ikewise the. nitrate or smlfate of nickel yield an impregnated product equally as improved as when employing iron salts. Manganese salts are slightly less eflicient when the ignition after impre nation is carried on at about 400 450 However, if the ignition of the bauxite impregnated with manganese salts is carried on at a higher temperature, i. e., 800-1000 0., the product appears to have the greatest stren h of any of the impregnated bauxites. n fact any of the heavy metal salts or combinations thereof which yield an oxide upon ignition maybe employed according to our invention, and

though we prefer to employ the nitrates and particularly ferric nitrate as being economical to use and most efi'ective, we do not limit ourselves thereto.

The process is applicable to any of the varieties of bauxites which are normally friable and soft upon activation according to the known methods. The impregnated-product may be reactivated after usev according to the methods heretofore used with very considerably less loss than normally occurs with the unimpregnated bauxite.

We claim:

1. Activated bauxite, structurally strengthened by an oxide of a heavy metal artificially deposited within the pores.

2. Activated bauxite impregnated with an oxide of a heavy metal.

3. Activated bauxite impregnated with an oxide of iron.

4. Activated bauxite prepared by impregnating the dehydrated mineral with a salt of a heavy metal and igniting to artificially produce the oxide of the heavy metal distributed throughout the bauxite, and having a hardness greater than that of the unimpregnated material.

5. The method of increasing the physical strength of activated bauxite which consists in impregnating activated bauxite with a salt of a heavy metal and igniting to artificially produce the oxide of the heavy metal distributed throughout the bauxite.

6. The method of increasing the physical strength of activated bauxite which consists in impregnating activated bauxite with an iron salt and igniting to artificially produce an oxide of iron distributed throughout the bauxite. 1

7 The method of increasing the physical strength of activated bauxite which consists in impregnating activated bauxite with a solution of iron nitrate and igniting to artificially produce an oxide of iron distributed throughout the bauxite.

8. The method of preparing activated bauxite which consists in activating the natural mineral bauxite, impregnating the activated product with solution of a salt of a heavy metal and igniting the impregnated substance to artificiall produce the oxide of the heavy metal distributed throughout the bauxite.

In testimony whereof, we aifix our signatures.

RAYMOND C. BENNER. ALFRED PAUL THOMPSON. 

